The invention relates to a bipolar grasping instrument with two clamping jaws movable relative to each other, electrically isolated from one another and each connectable to a pole of an electric high-frequency voltage source, each of the clamping jaws comprising two clamping elements arranged in spaced relation to one another, forming between them a longitudinal slot and each having a clamping surface, and with a cutting device comprising a cutting element displaceable in the longitudinal slots of the clamping jaws and having a cutting edge.
With bipolar grasping instruments it is possible to coagulate tissue in the grasped area so as to control bleeding in this area.
It is known to coagulate certain areas, for example, in vessels, with such instruments and to then transect the vessels by an incision in this coagulated area, with the risk of bleeding being minimized by the preceding coagulation. This requires two completely separate procedural steps which are usually performed with different instruments, namely, on the one hand, the coagulating with a bipolar grasping instrument, and, on the other hand, the transecting of the coagulated tissue with a cutting device.
Bipolar grasping instruments with an integrated cutting device are also known (company prospectus of CIRCON, TRIPOLAR Cutting Forceps; U.S. Pat. No. 5,458,598). In this instrument, the clamping jaws of the grasping instrument are divided by longitudinal slots into two clamping surfaces arranged adjacent one another, and a cutting element provided with a cutting edge, which transects parts of tissue held between the clamping surfaces after the coagulation, can be pushed into the longitudinal slots in the longitudinal direction of the instrument. In this previously known instrument, different drive mechanisms must be provided for closing the clamping jaws to bring about the coagulation and for advancing the cutting element of the cutting device. This instrument, which is preferably designed as a tubular-shafted instrument, is, therefore, of relatively complicated design, and, in addition, the user of this instrument must operate two separate drive mechanisms in order to first grasp and then transect tissue.
The object of the invention is to so design a bipolar grasping instrument of the generic kind that operation is simplified, in particular, by the user only requiring one actuating mechanism for first grasping and then transecting tissue.
This object is accomplished with a bipolar grasping instrument of the kind described at the outset, in accordance with the invention, in that the cutting element is arranged in the longitudinal slot of the one clamping jaw such that its cutting edge is contained in the longitudinal slot between the clamping elements of this clamping jaw and does not extend beyond its clamping surfaces in the direction towards the other clamping jaw, and in that the clamping elements of this clamping jaw are elastically movable relative to the cutting element opposite to the closing movement of the clamping jaws so far that the cutting edge of the cutting element projects beyond the clamping surfaces.
Thus, at the start of the closing movement of the clamping jaws, the cutting element is accommodated in the longitudinal slot of the one clamping jaw such that the cutting edge of the cutting element is contained within the longitudinal slot and, therefore, does not become operative. In this case, the instrument operates like a conventional bipolar grasping instrument in which the clamping surfaces are placed against the tissue to be grasped without the cutting element appearing at all. In this part of the closing movement, coagulation can be brought about by applying a high-frequency voltage in the conventional way, and, after the coagulation, the bipolar grasping instrument can also be removed again like a conventional bipolar grasping instrument.
If, on the other hand, the closing movement is continued with this bipolar grasping instrument after the coagulation, the clamping jaws are moved together so forcefully that the clamping elements of the clamping jaw carrying the cutting device are moved elastically opposite to the closing movement of the clamping jaws, and this releases the cutting edge of the cutting device which owing to the elastic displacement of the clamping elements then protrudes beyond the clamping surface. Therefore, the instrument is now a cutting instrument in which the cutting element can reach into the longitudinal slot of the other clamping jaw, thereby transecting the tissue engaged between the clamping jaws. This cutting movement immediately follows the normal closing movement of the clamping jaws. The user only has to actuate one drive mechanism. In the event of light actuation, the tissue to be coagulated is merely clamped and held firmly, but upon forceful closure of the clamping jaws, the tissue parts held between the clamping jaws are additionally severed.
In a first preferred embodiment provision is made for both the cutting element and the clamping elements to be constructed integrally with the clamping jaw, and for the cutting element to be a rigid part of the clamping jaw, while the clamping elements are joined to the remaining parts of the clamping jaw via elastically deformable areas. In particular, the elastically deformable areas can be formed by elastically bendable webs of low height.
In another embodiment provision is made for the clamping jaw to be of two-part construction, with a first rigid part comprising the cutting element and the bearing of the clamping jaw on the grasping instrument, and with a second part comprising the clamping elements and being elastically movably mounted on the first part.
The clamping elements may, for example, be elastically pivotably mounted on the first part.
It is advantageous for the second part to be of U-shaped design with two parallel legs forming the clamping elements and a web joining these legs and closing off the longitudinal slot towards the distal end of the clamping jaw, and for the second part to be rotatably mounted at the free ends of the legs on the first part. This results in a very stable arrangement of the second part of the clamping jaw carrying the clamping surfaces.
The longitudinal slot in the other clamping jaw, which does not have any cutting device, is preferably closed at both ends thereof, so that the cutting device enters this longitudinal slot closed on all sides during the cutting procedure, and this also contributes towards the other clamping jaw forming a very stable arrangement.
The following description of preferred embodiments of the invention serves in conjunction with the drawings to explain the invention in further detail.